Technical Field
The disclosure relates in general to a semiconductor device and a method for manufacturing the same, and more particularly to a semiconductor device having gate structure with reduced threshold voltage and a method for manufacturing the same.
Description of the Related Art
Size of semiconductor device has been decreased for these years. Reduction of feature size, improvements of the rate, the efficiency, the density and the cost per integrated circuit unit are the important goals in the semiconductor technology. The electrical properties of the device have to be maintained even improved with the decrease of the size, to meet the requirements of the commercial products in applications. Besides complete profiles of the related elements of a semiconductor device, the electrical characteristics of the related elements are also the major concern during design of scale-down device. Typically, the gate length of the gate structure decreases, the threshold voltage (Vt) increases.